1. Field of Use
This invention relates to the uniform illumination of surfaces, which may be specular or irregular, and more particularly, to the uniform illumination of machine readable codes, symbologies and the like that may be applied to such surfaces, to facilitate imaging and decoding of any such symbology applied directly to such surfaces or to media that is, in turn, applied to such surfaces.
2. Description of the Prior Art
It is quite often necessary to determine the existence, location or characteristics of an article through automated means for automated purposes. Robotic handling of parts for processing such as machining or assembly purposes and automated sorting, transportation, manipulation and other handling of parts, components, packages and the like usually requires that some form of machine readable code or symbology be applied to the article. U.S. Pat. No. 5,567,927 patented to R. W. Kahn on Oct. 22, 1996 for xe2x80x9cApparatus For Semiconductor Wafer Identificationxe2x80x9d and U.S. Pat. No. 5,631,456 patented to K. L. Kost on May 20, 1997 for xe2x80x9cReflection Control Apparatusxe2x80x9d are exemplary of such product marking. At times it is convenient to apply the symbology to a media such as a pressure sensitive label. Other times it is more desirable and possibly efficient to apply the symbology directly to the article. The symbology may be a conventional bar code, a stacked bar code or other 2-D symbology.
Machine reading of symbology, as by a stationary or hand-held reader or imager, requires proper illumination of the targeted symbology. This may present problems if the media carrying the symbology is applied to an irregular or curved surface. The problems are more pronounced if the symbology is applied directly to the article and the article surface is normally specular and/or the article""s surface is irregular.
When the symbology reader or imager is to be hand-held it is usually most desirable to minimize its size and weight. To do so while at the same time providing for uniform and diffuse illumination for the symbology may and has created problems.
Some hand-held symbology readers, such as that shown and described in U.S. Pat. No. 4,818,856 patented to T. Matsushima et al. On Apr. 4, 1989 for xe2x80x9cOptical Information Reading Apparatusxe2x80x9d, attempt to effect reading of the symbology with ambient light; but, since ambient light is not always sufficient to facilitate symbology reading such devices may be unacceptable. Other hand-held symbology readers, such as those shown and described in U.S. Pat. No. 5,349,172 patented to A. Roustaei on Sep. 30, 1994 for xe2x80x9cOptical Reading Headxe2x80x9d and in U.S. Pat. No. 5,378,883 patented on Jan. 3, 1995 to E. P. Batterman et al for xe2x80x9cOmnidirectional Wide Range Hand-Held Bar Code Readerxe2x80x9d, provide their respective LED or Xenon tube illumination either directly through a window of the reader or through lenses and then directly through a reader window. The resulting illumination of the symbology may thus be irregular and not diffuse and, as such, unacceptable.
Other hand-held symbology readers, such as those shown and described in U.S. Pat. No. 5,530,233 patented to M. Krichever on Jun. 25, 1996 for xe2x80x9cBar-Code Scanner With Quasi-Retroreflective Light Collectionxe2x80x9d and in U.S. Pat. No. 5,468,949 patented on Nov. 21, 1995 to J. Swartz et al, for xe2x80x9cPortable Laser Diode Scanning Headxe2x80x9d, direct their respective laser sources of illumination into the hand-held devices. However, these devices also incorporate motor driven mirrors to scan the illumination across the symbology. Laser illumination reflected off a specular mirror surface is neither diffuse nor uniform and the use of mirrors and motors add unacceptable weight and cost to the device. Other hand-held devices, such as those shown and described in U.S. Pat. No. 5,602,376 patented to E. P. Coleman on Feb. 11, 1997 for xe2x80x9cHand-Mounted Optical Scanner Systemxe2x80x9d utilize laser illumination with two mirrors, one of which is rotated; or as shown and described in U.S. Pat. No. 5,184,004 patented to S. Uede on Feb. 2, 1993 for xe2x80x9cOptical Code Readerxe2x80x9d utilize an inwardly facing light source and a pair of mirrors with specular surfaces, are also unacceptable for the intended uses for the above reasons.
U.S. Pat. No. 5,187,611 patented on Feb. 16, 1993 to T. P. White et al for xe2x80x9cDiffuse On-Axis Light Sourcexe2x80x9d; U.S. Pat. No. 5,585,616 patented on Dec. 17, 1996 to D. L. Roxby et al for xe2x80x9cCamera For =Capturing And Decoding Machine-Readable Matrix Symbol Images Applied to Reflective Surfacesxe2x80x9d; and U.S. Pat. No. 5,313,373 patented on May 17, 1994 to J. A. S. Bjorner et al for xe2x80x9cApparatus For The Uniform Illumination Of A Surfacexe2x80x9d all direct their respective sources of illumination generally towards the target to be illuminated. The alleged diffuse and uniform illumination requires incorporation of diffusing members which unacceptably absorb light and reflect some light back into the device. Diffusers, furthermore, add weight and cost to the devices. White et al additionally requires beam splitters; while Roxby et al, must utilize a head with a white matte finish interior surface to diffuse ambient light reflected off the symbology and into the device towards the sensor, and Bjorner et al must utilize a shroud with inside surfaces that are both black and white. A. Brandorff et al, in U.S. Pat. No. 5,408,084 patented on Apr. 18, 1995 for xe2x80x9cMethod And Apparatus For Illuminating And Imaging Of A Surface Using 2-D LED Arrayxe2x80x9d, also incorporates a shroud but one with a specular, thin aluminum reflective inner surface; while Y. Sakai et al, in U.S. Pat. No. 5,572,008 patented on Nov. 5, 1996 for xe2x80x9cOptical Information Reading Apparatus With Concave Mirrorxe2x80x9d directs the laser illumination up towards a concave mirror then to a rotating mirror and then to a pattern mirror all of which unacceptably affect their respective devices.
U.S. Pat. No. 5,325,276 patented to K. Sullivan on Jun. 28, 1994 for xe2x80x9cLighting Apparatus For The Computer Imaging Of A Surfacexe2x80x9d and U.S. Pat. No. 5,461,417 patented on Oct. 24, 1995 to T. P. White et al for xe2x80x9cContinuous Diffuse Illumination Method And Apparatusxe2x80x9d respectively must utilize walls with electroluminescent panels and a dome that is backlit by two light sources to accomplish their intended target illumination. While J. B. Powers et al in U.S. Pat. No. 5,623,137 patented on Apr. 22, 1997 for xe2x80x9cIllumination Apparatus for Optical Readersxe2x80x9d, is not specific as to the direction the illumination source faces but does utilize complex configured specular mirrors to direct the illumination towards the symbology; and K. L. Kost et al, previously mentioned, requires a circle of LED""s facing inwardly to illuminate the white walls of an upper chamber. However, the resulting illumination must find its way through a relatively small opening leading from that chamber. Because of that relatively small opening the Kost et al device is not suitable for illuminating a symbology with diffuse light from a wide range of angles while retaining a small size apparatus.
It is therefore an object of this invention to provide new and novel surface illumination apparatus.
It is another object of this invention to provide new and novel methods of surface illumination.
It is yet another object of this invention to provide new and novel diffuse, high efficiency illumination of surfaces which carry machine readable coded information.
It is another object of this invention to provide new and novel illumination of specular and otherwise irregular surfaces upon which there is disposed machine readable coded symbology.
It is yet still another object of this invention to provide new and novel apparatus and methods for hand-held illumination of machine readable coded symbology.
It is a further object of this invention to provide new and novel apparatus and methods for hand-held, diffuse, high efficiency, illumination of machine readable coded symbology.
It is yet a further object of this invention to provide new and novel apparatus and methods for hand-held illumination of machine readable, coded symbology applied directly to parts and components.
It is yet still a further object of this invention to provide new and novel apparatus and methods for casting or projecting illumination from a uniformly radiating wall upon machine readable coded symbology.
It is yet still a further object of this invention to provide new and novel apparatus and methods for directing an area of illumination or a wall of illumination upon parts, components and the like to facilitate automated processing thereof.
It is yet still a further object of this invention to provide new and novel apparatus and methods for applying illumination to symbology carried by parts, components and the like to facilitate decoding of the symbology.
It is yet a further object of this invention to provide new and novel hand-held apparatus and methods for applying diffuse, high efficiency, uniform illumination to symbology directly applied to parts, components and the like to effect decoding of the symbology.
It is yet still another object of this invention to provide new and novel arrangements of light emitting diodes to provide diffuse, high efficiency illumination.
It is yet still another object of this invention to provide new and novel arrangements of light emitting diodes for hand-held imagers of symbology.